For example, a 30,000 BTU 2.5 ton air conditioner is made to effectively cool a house of between 1,200 and 1,500 square feet. A slightly larger 3,600-3 ton unit is designed for homes of 1,500 to 1,800 square feet. The easiest way to calculate the size of the air conditioner in a house is to use a general rule. According to this common but somewhat inaccurate method, 1 ton of cooling capacity is needed for every few square feet of living space.

While there is some controversy over the exact quantity, a frequently used quantity is 600 square feet. A 2.5-ton unit, then, would theoretically fit in a 1500 square foot house. 1.5-ton air conditioners can cool 600 to 900 square feet of space. 2-ton units can cool spaces from 901 to 1200 square feet.

2.5-ton units can cool between 1201-1500 square feet, etc. Now you can answer this question. A 1.5-ton air conditioning unit covers 900 square feet of living space. The size chart below is useful to help you determine the approximate size requirements for your central air conditioner.

For example, the CKL24-1 model is a 2-ton unit. Why? There are 12,000 Btu per ton. The number 24 in the model number indicates that the unit has 24,000 Btu divided by 12,000 Btu per ton, which is equivalent to 2 tons. Use the following conversion information to determine the size of your current system (use the system model number, NOT the serial number).

Next, to calculate the power of a gas oven, multiply its efficiency index by the nominal input value indicated for the actual heat output in BTU. For example, if a furnace has a rated input power of 100,000 Btu and an efficiency rating of 80%, it will produce. For this example, using a furnace with an 80% efficiency, the previous 2,000-square-foot house would require a 100,000 Btu inlet furnace that will produce the necessary heat production of 80,000 Btu. If you install the 5-ton unit and find that it's too small, you can always add a 1- or 2-ton unit to areas where the 5-ton unit doesn't have the proper air conditioning.

I've had two estimates: one person suggests 3 tons because of a major mold problem that could have been caused by Florida's humidity and because the air conditioning unit is too large. As a general rule, centralized and mini-split air conditioners can operate between 450 and 600 square feet per ton of air conditioner depending on the climate and load calculation factors related to your home, such as insulation value, window quality, etc. When looking for a quick answer to the amount of air conditioner the energy you'll need to properly cool a 1,300-square-foot space, the answer is 23,000 BTU per hour of air conditioner energy. One problem with estimating the size of the air conditioner based on square feet is that every home is different.

Another method for sizing air conditioners is to determine the size of the air conditioning system that is currently in operation.